user manual

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Bosch Security Systems | 04-2003 | 3922 988 43318 en
Digital Congress Network | Installation and Operating Manual | Chapter 12 - Environmental Conditions & Maintenance
en | 12-1
System
Chapter 12. Environmental
Conditions and
Maintenance
12.1 System
Where appropriate use cable ducts for extension and mains cables. In order to identify such cables
consider using cable tallies. Trunk-lines where appropriate should be divided into manageable
geographic locations - for example- use one trunk-line for committee members or dignitaries seated
on a stage, and reserve, if appropriate one trunk-line for interpreter desks etc.. It is recommended
that the chairman unit and interpreter desks are connected at the beginning of a trunk-line and not at
the end. In public areas where connectors and cables could be trampled on, consider using protective
metal covers according to the existing protection specification.
12.2 Public areas
12.2.1 Lighting
When placing contribution and channel selector units comprising an LC-display, ensure that the
displays are positioned in such away as to avoid direct lighting or sunlight. The recommended viewing
distance (due to the size of characters) is at arms length 1.5 m with a minimum light level of 50 lux,
or even shorter for channel selector units without back-lighting so as to operate the unit while still
having a good viewing angle.
12.2.2 Public displays (placement/viewing distance)
Place public displays in positions where they can be easily viewed by all participants concerned. Avoid
placement in direct lighting or sunlight. The size and viewing distance for public displays shall be
selected depending on the visibility criteria for each specific system. Aspects such as viewing distance,
character size for hall displays, contrast an brightness under the usual lighting conditions shall be taken
into account. Advise to be given by the equipment suppliers.
12.2.3 Public walkways
In public areas ensure that the cables attached to the system units, including extension cables, are run
and laid out in a neat and tidy manner where they do not interfere and hinder public walk ways.
12.2.4 Headphones with interpreter systems
Where appropriate place headphones/headsets with the relevant contribution units and interpreter
desks.
NOTE: Acoustic feedback, causing ‘Larsen’ effect (howling), is possible when connected
headphones/headsets reproducing the floor channel with a high volume, come too close to
an activated microphone. The minimum distance recommended between microphone and
headphones/headsets to avoid the ‘Larsen’ effect, depends on the type of headphones/
headset, the volume setting and if worn or laid down on a desk or table. User should be
instructed to keep sufficient distance or to set the volume level not louder than necessary.
12.2.5 Recommended speaking distance
The recommended speaking distance from microphones is 30 cm (1 ft.).
12.3 Technical rooms
It is recommended that in technical rooms where DCN’s central control equipment is housed the
following conditions should be met:
• When units are mounted in a 19” rack ,sufficient rack space is required between heat generating
units to allow proper ventilation. Proper precautionary measures should also be taken inside the
rack (e.g. forced ventilation inside racks) to keep the ambient temperature well below the
maximum allowed temperature so as to extend the life-time of the equipment.
Refer to Chapter 13.. ‘Technical data’ for the allowed temperatures.
• Ensure that the area is a dust-free environment.
• Ensure adequate air-conditioning.
• Ensure adequate ventilation.
• Ensure adequate lighting. But ensure that the lighting does not impede the central operators.
• Do not place objects on top of the units, which could fall into vents or which could cover them
and prevents proper cooling of the units electronics. This could infiltrate into the unit which
could cause trouble such as fire and electric shock.
• Do not expose units to rain or excessive moisture to avoid the risk of shock or permanent dam-
age to the system units.
• Do not attempt to remove the top cover of the Central Control Unit, Audio Media Interface
Unit and Extension Power Supply Unit as you will be exposed to a shock hazard. The covers
should only be removed by qualified service personnel. The units are designed for indoor use
only. Please refrain from subjecting the units to vibration, and never place the units near or over
a radiator, heat grill or in direct sunlight.
• In PC based systems, be warned that placing a magnet or loudspeaker system in the vicinity of
the PC will corrupt data files stored on the hard or disk or floppy disks.
WARNING: Damage to the power cable may cause fire or a potential shock hazard.